Invited Review: Effects of flow on vascular endothelial intracellular calcium signaling of rat aortas ex vivo

Abstract

To study the effects of flow on in situ endothelial intracellular calcium concentration ([Ca2+]i) signaling, rat aortic rings were loaded with fura 2, mounted on a tissue flow chamber, and divided into control and flow-pretreated groups. The latter was perfused with buffer at a shear stress of 50 dyns/cm2 for 1 h. Endothelial [Ca2+]i responses to ACh or shear stresses were determined by ratio image analysis. Moreover, ACh-induced [Ca2+]i elevation responses were measured in a calcium-free buffer, or in the presence of SKF-96365, to elucidate the role of calcium influx in the flow effects. Our results showed that 1) ACh increased endothelial [Ca2+]i in a dose-dependent manner, and these responses were incremented by flow-pretreatment; 2) the differences in ACh-induced [Ca2+]i elevation between control and flow-pretreated groups were abolished by SKF-96365 or by Ca2+-free buffer; and 3) in the presence of 10−5 M ATP, shear stress induced dose-dependent [Ca2+]i elevation responses that were not altered by flow-pretreatment. In conclusion, flow-pretreatment augments the ACh-induced endothelial calcium influx in rat aortas ex vivo.